1. Field of the Invention
The present invention relates to a movable contact point for a switch.
2. Description of the Related Art
For example, Japanese Patent Laid-Open Publication No. 2012-197022 proposes various kinds of switches configured such that movable contact points making pressure contact with fixed contact points are moved in the circumferential direction around a rotary shaft, thus connecting/disconnecting the fixed contact point and the movable contact point.
FIG. 4 is an exploded perspective view explaining the configuration of an inhibiter switch 10 according to the conventional example that is represented by the inhibiter switch disclosed in Japanese Patent Laid-Open Publication No. 2012-197022. It should be noted that FIG. 4 is a cross section showing the periphery of a shaft portion 51 in a movable board 5.
FIGS. 5A to 5C are diagrams explaining a movable contact point 7X according to the conventional example.
A body case 4 of the inhibiter switch 10 is formed by coupling a cover 3 to a peripheral wall 24 that surrounds an area of a pole board 2 where fixed contact points 8 are disposed, and the movable board 5 provided with the movable contact points 7X is provided inside the body case 4 to be rotatable around an axis line X.
The movable board 5 includes a cylindrical shaft portion 51 and a contact point holding portion 52 extending in a radial direction (radial direction of the axis line X) from the shaft portion 51, and each of the movable contact points 7X is accommodated in an accommodation hole 53 formed in the contact point holding portion 52 together with a spring Sp.
Each of the movable contact points 7X projects downward to the pole board 2-side from the accommodation hole 53 by an urging force acting from the spring Sp, and is configured to make pressure contact with the fixed contact point 8 exposed on an upper surface of the pole board 2 in a state where the movable board 5 is incorporated in the body case 4.
A shaft rotating in association with an operation of a shift lever is coupled to the shaft portion 51 of the movable board 5. When the shift lever is operated, the contact point holding portion 52 extending in the radial direction from the shaft portion 51 rotates around the axis line X in association with the operation of the shift lever. Thereby, the movable contact point 7X having made pressure contact with the fixed contact point 8 moves (slides) in a circumferential direction around the axis line X.
The movable contact point 7X has a basic configuration formed by bending one sheet of metallic plate in a U-letter shape, and as shown in FIG. 5A, a sliding portion 72 that slides on the fixed contact point 8 is positioned between side wall portions 71 disposed in parallel to each other to have an interval therebetween in the sliding direction of the movable contact point 7X.
In a side view, an outer periphery of the sliding portion 72 is formed in an arc shape, and the movable contact point 7X causes the outer periphery of the sliding portion 72 to make pressure contact with the fixed contact point 8 in the inhibiter switch 10.
Here, when the shift lever is operated, the movable contact point 7X is operated to slide on the fixed contact point 8 toward one of the sliding directions. Repetition of the sliding of the movable contact point 7X by the operation of the shift lever causes wear of the sliding portion 72 having made pressure contact with the fixed contact point 8, such that a thickness W1 of the sliding portion 72 becomes thin.
Then, support strength to the side wall portions 71 disposed to oppose across the sliding portion 72 is the weaker as the thickness W1 of the sliding portion 72 becomes thinner.
When the movable contact point 7X that slides on the fixed contact point 8 in association with the operation of the shift lever reaches a predetermined angular position in the circumferential direction around the axis line X, the movable contact point 7X gets over a step portion 9 formed in the pole board 2 to be spaced apart from the fixed contact point 8.
Therefore, the movable contact point 7X is subjected to stress in accordance with an operation force of the shift lever from abutment points P1 and P2 to the accommodation hole 53 that accommodates the movable contact point 7X therein at the time of sliding on the fixed contact point 8 or getting over the step portion 9 (refer to FIG. 5B).
Consequently, when the thickness W1 of the sliding portion 72 becomes thin to lower the support strength to the side wall portions 71, the side wall portions 71 cannot be held in a state of being disposed in parallel to each other against the acting stress, and are inclined in a direction of narrowing the interval of each other.
In addition, when the inclination of each of the side wall portions 71 in the direction of narrowing the interval of each other is large by the repetition of the sliding of the movable contact point 7X, the movable contact point 7X is largely deformed (refer to FIG. 5C), leading to the difficulty of causing the movable contact point 7X to be connected to/disconnected from the fixed contact point 8 in an appropriate position (angular position).
It is possible to extend a period (lifetime of the movable contact point 7X) for which the movable contact point 7X is connected to/disconnected from the fixed contact point 8 in an appropriate position by increasing the thickness W1 of the sliding portion 72.
However, since the movable contact point 7X is formed by bending one sheet of metallic plate, when the thickness (thickness of the metallic plate) of the sliding portion 72 is increased to meet a demand for recent long life, the thickness of the side wall portion 71 is also increased. Therefore, the movable contact point 7X is upsized.
Then, since a size of the movable contact pint 7X to the accommodation hole 53 of the contact point holding portion 52 is increased, the movable contact point 7X cannot be incorporated in the body case 4 of the inhibiter switch 10.
Therefore, there is a demand for preventing a deformation of the movable contact point without the upsizing thereof to extend the lifetime of the movable contact point.